Twenty minutes after completing the victory of her young life, CiCi Bellis was asked how she did it.

Her response was a runaway, over-the-moon laugh.

"I'm trying to figure that out, too," she said Wednesday, sounding genuinely amazed.

The 17-year-old -- no, that is not a typo -- stunned No. 6-ranked Agnieszka Radwanska 6-4, 2-6, 6-2 at the Dubai Tennis Championships. In her first main draw matches of 2017, the California teenager has now beaten three top-50 players in three days.

On Wednesday, CiCi Bellis won her first career match against a top-10 player. Tom Dulat/Getty Images

Catherine Cartan Bellis will meet former world No. 1 Caroline Wozniacki in the Thursday quarterfinals of this WTA Premier 5 event.

"Oh, gosh," Bellis told ESPN.com by phone. "I played a really good match. I'm playing the best tennis of my life."

Admittedly, it's a small sample size.

Bellis, currently ranked No. 70, is the youngest player in the WTA top 100. Her unexpected win over Radwanska -- a former Grand Slam finalist and No. 2-ranked player -- sent the statisticians to the record books for precedents. Turns out, Bellis is:

The second-youngest player to reach the quarters in 17 years of play at Dubai.

The youngest American to defeat a top-10 opponent since Wimbledon 2009, when Melanie Oudin eliminated Jankovic.

Younger players, obviously, are at both a mental and physical disadvantage with respect to their more experienced opponents. Bellis, who was born perilously close to the turn of the century, in April, 1999, has worked hard to close both gaps.

While the WTA web site lists her at 5-foot-7, 110 pounds, she says she's put on some more muscle in the gym and is closer to 120. After breaking Radwanska's serve three straight times in the third set and winning 21 of 33 points on her second serve, it would be best not to challenge Bellis' mental toughness.

"I was trying not to think about, 'I'm about to beat No. 6 in the world,'" Bellis said. "I had to tell myself to stay calm and not get too caught up in the moment.

"I've won before against top players, but it was more of a one-match thing. I couldn't keep it up because I just wasn't as strong physically. Now I feel like I can hang with the top players."

Bellis, who turns 18 in April, is approximately half the age of No. 1-ranked Serena Williams and more than a decade behind No. 2 Angelique Kerber.

Kei Nishikori, No. 5 in the ATP rankings, was eliminated from the Rio Open in the first round after a straight sets loss against home favorite Thomaz Bellucci.

2 Related

Bellis missed the beginning of the season with two related left leg injuries, a strained hamstring and a gluteus maximus. Her 2017 WTA debut came a week ago when she beat No. 59 Shuai Peng in first round of qualifying at Doha, but then lost in the second. Bellis surprised No. 27-ranked Yulia Putintseva 6-1, 7-5 in Dubai's first round, rallying from 5-1 down in the second set. Bellis then beat No. 41-ranked Laura Siegemund 7-5, 7-6 (3).

As Bellis noted, she has already had her share of scoring upsets. At the 2014 US Open, the then 15-year-old made headlines by defeating No. 13 Dominika Cibulkova in the first round for her first top-20 win. But that came with an asterisk: Bellis was the youngest player to win a match at US Open since 1996 Anna Kournikova, the poster child for unfulfilled promise. Kournikova -- who is today 35, the same age as Williams -- famously never won a WTA-level title and was retired by the age of 21 with a variety of back and spinal issues.

Bellis, however, has made swift progress. She won three times in qualifying at last year's US Open, then won two main-draw matches before losing to the eventual champion Kerber. That put Bellis in an awkward position; she was still an amateur and considering a scholarship from Stanford University, but her US Open prize money amounted to nearly $150,000. Bellis sat down with her parents, IMG agent Marijn Bal, coach Anibal Aranda of the USTA and hitting partner Tom Gutteridge and announced two weeks later she was turning professional (and collected the cash).

"It was the right decision," Bellis said.

And results of the past three days alone would seem to support it.

Bellis finished the 2016 in a blur, reaching the quarterfinal in Quebec City, then winning two ITF titles in Canada and concluding with the WTA 125K Series title in Honolulu. Those last three events gave her 15 consecutive match wins.

Her short-term goal?

Land more first serves, get stronger and break into the top 50.

These three wins will get her around No. 56 when the WTA rankings come out next Monday. A win over the resurgent Wozniacki would check that top-50 box off -- and it's only her second event of the year.

"Long term, I'm trying to be the best player I can be," Bellis said. "As long as I stay healthy and keep getting better, that will take me pretty far."